中文摘要：

直流配电网是未来配电系统发展的新趋势,其电能质量问题是需要关注的重要问题之一。其中纹波的影响因素多、涉及面广,是一种常见的直流电能质量问题。结合直流配电网的拓扑结构、变流器交流侧的特性,分析由于交流负荷非理想特性及交流电源不理想因素而引起的直流纹波形成机理。在此基础上,对交流接入端三相对称和不对称情况下正序谐波、负序谐波及零序谐波在直流侧产生的纹波及相互间的叠加情况进行频域分析,建立了纹波叠加特性与交流谐波次数和相位的关系。仿真结果验证了理论分析的正确性。

英文摘要：

DC distribution network is a new trend for future distribution systems. Power quality problem will be an attention focus in its application. For this problem, ripple is influenced by many factors. In order to clarify issues related to ripple, this paper considers topology and characteristics of AC side converter and analyzes non-ideal characteristics of AC load and other undesirable factors of AC grid causing DC ripple. On this basis, from point of positive, negative and zero sequence harmonics, DC side ripple and its superimposition in condition of AC three-phase symmetric and asymmetric cases are studied in frequency domain. Relationship between ripple superposition and AC harmonic characteristics is also presented. Simulation examples of DC distribution network verify validity of theoretical analysis.